Question: When did was Natalia Revuelta Clews the partner of Fidel Castro.
Paraphrase: At what time was Natalia Revuelta Clews the partner of Fidel Castro.
SPARQL (Wikidata): SELECT ?value WHERE { wd:Q11256 p:P451 ?s . ?s ps:P451 wd:Q19516418 . ?s pq:P580 ?value}